DIY Homemade laser diode driver

[stump56]

sorry i should have know that 8 megs would be to big.

 

[mw1111]

much better! now i can see it lol

 

[stump56]

so does anyone have anything to say about this.

 

[Gazoo]

What is the voltage and current on your test load?

 

[Daedal]

Stump, it looks good in the pictures... let us know what you get on the test load.

What's your input voltage?
What's your output voltage?
Is your current looking good?



GL;
DDL

 

[stump56]

is 5 0hms a good test load?

 

[Daedal]

Probably, ya

I would try that and some LEDs

--DDL

 

[stump56]

DDL I have 5 Ohms across the adj. and a 10 Ohm test load and the results are: Output 2.34v and 208 ma

 

[Gazoo]

You should be getting closer to 250ma's. What is the voltage of the batteries with the load applied.

 

[stump56]

5.3 volts

 

[Gazoo]

The regulator is beginning to drop out. You really need a minimum of 6 volts for it to regulate properly...this explains why you are not seeing 250ma's.

The formulas are 1.25/ohms = current.
1.25/current = ohms.

1.25 is the reference voltage the regulator uses and you should always see that voltage between the output and adjust pins of the regulator.

 

[stump56]

Should i use a 9 volt then

or will the drop be less with the diode since i am using a 10 ohm load now

 

[stump56]

i just tried a silicon diode instead of the resistor for the load and got 250 ma but the out voltage was over 5.

 

[Gazoo]

Don't use those little square 9 volt batteries as they will not power it for long and are not made to deliver high currents.

If it was me I would get a 6 AA or AAA battery holder. You could use Alkaline or Nimh batteries and it would a no muss no fuss solution. Or you could use a pair of AA li-ion batteries.

At 5.3 volts, I the regulator will be out of regulation with the GB diode hooked up. I know this isn't what people want to hear but others have had problems even using a pair of CR123's. The voltage sags to the point the regulator begins to drop out.

 

[Gazoo]

i just tried a silicon diode instead of the resistor for the load and got 250 ma but the out voltage was over 5.

Because you are not putting enough of a load on it. A silicon diode has about a .7 volt voltage drop. You need 4 silicon diodes hooked in series to simulate appx. what a GB diode will pull.

 

[stump56]

what type of li ion AA Will the energizer type work i thought they were 1.5 volts apiece